What is the 3D software that you use frequently and why (XSI, 3D Max, Maya, 4D)?

3ds Max coz most of companies in the Middle East uses it

3d Max

when it comes to a quick fast projects i use max, easy and fair rendering time, but it crashes alot, xsi is very strong stable software, modeling and animation are amazing, will take time to learn but once you learn it, will give the power to create or animate anything.

i use the both Softwares but i use C4d frequently because the type of my work (Motion Graphics) and i use3Ds Max for the Complex modeling like Characters, Particles and other stuff..

Both3D MAX and Maya  Its depends on requirement.

maya

I use Blender3D and Vue, also used3D studio max and Lightwave in the past.
Why Blender, A couple of years ago I had a licence issue with my Software, the moved to blender and fell in love with it.
I believe blender is the best modeling tool and is olso best in UV Mapping.

maya ,cinema4d

3d studio max . 

For Modeling =3D Studio Max & ZBrush For Animation = MAYA & CINEMA4D For Rendering = VRay & Mental Ray You can use all of them to finalize your project

3d max because I love it :)